Winning metals by electrolysis in the presence of molten salts is an area in which increasing research is being carried out. An embodiment of this process is known from U.S. Pat. No. 2,757,135. In this event a metal halide, titanium tetrachloride, is supplied to the electrolysis cell by introducing into the salt melt. In practice, that process has to be carried out with a diaphragm that prevents the flow of titanium in lower valencies to the anode. If this were not done, the titanium would be re-oxidized at the anode to tetravelent titanium and would thus give rise to a loss of current and raw material. Furthermore, the build-up of titanium in the diaphragm shortens its life, which is a significant disadvantage.